A Novel Method to Maintain Alignment Accuracy in Bonding Process Utilizing Resin as an Adhesive Material

S.-S. Lee, M. Kondo, R. Ishibashi, K. Kinoshita, S. Kishida
Tottori University, JP

Keywords: bonding, alignment, accuracy, resin, near infrared, MEMS

Summary:

In this paper we have firstly reported that a novel method to maintain alignment accuracy in wafer bonding process utilizing resin as an adhesive material. We have proposed tentatively localized bonding method with 1100 nm near infrared (NIR) radiation that is transparent to Si wafers. With the aid of our localized tentative bonding process and experimental setup for it, we have achieved about 4 to 5 times more accurate alignment in micrometer order between wafers for typical case than without it. In order to prevent the wafers from shifting relative to each other when applying temperature and pressure after alignment, we apply NIR radiation spots after alignment. The NIR radiation spotted areas are locally heated and tentatively bonded, which play a role of anchors. By doing that without additional any fabrication process, we have achieved the maintenance of alignment accuracy even when applying temperature and pressure using commercially available bonding equipment.